Systems and Methods Based on Radiation Induced Heating or Ignition of Functionalized Fullerenes

ABSTRACT

A method of irradiating a target region containing at least one fullerene comprising molecule promotes the heating or combustion of the target region. The heating method can be employed in a variety of applications including: selective targeting and destruction of cancer cells, detonation of explosives, ignition of a combustible mixture, photolithographic processes, and writing of optical storage media.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 12/479,300, filed Jun.5, 2009, which is a continuation-in-part of International PatentApplication No. PCT/US2007/084956, filed Nov. 16, 2007, which claims thebenefit of U.S. Provisional Patent Application Ser. No. 60/868,633,filed Dec. 5, 2006, the disclosures of which are hereby incorporated byreference in their entirety.

This invention was made with government support under Contract No.EEC9402989 awarded by the National Science Foundation. The governmenthas certain rights in the invention.

FIELD OF THE INVENTION

The invention relates to systems and methods based on the radiationinduced heating or ignition of carbon nanomaterials, more particularlyto heating or ignition of functionalized fullerenes.

BACKGROUND

Many current industrial processes that utilize a fuel or an oxidationreaction often require an initiation stimulus, or an ignition source, tostart the reaction to release energy (e.g., heat, light). A device whichachieves this goal is a critical system component for most combustionprocesses. Although many different ignition methods exist, the mostpopular is the electric spark igniter. However, spark igniters requirehigh-energy input supplied by a high-voltage circuitry and by its natureis a single-point stimulus method. Other ignition methods, such asplasma jet injection or flame jet initiation and high-power laserignition, are all bulky, heavy, and expensive to operate.

There have been some recent reports of optical ignition of carbonnanotubes in oxidizing gaseous ambients, such as in air. For example,researchers have reported that single-walled carbon nanotubes ignitewhen exposed to a conventional photographic flash (Ajayan et al.,“Nanotubes in a Flash-Ignition and Reconstruction”, Science, Vol. 296,Apr. 26, 2002). This photoeffect is disclosed to occur for single-walledcarbon nanotubes prepared by carbon arc, laser ablation, or chemicalvapor deposition techniques upon exposure to a camera flash at closerange. Ignition and burning are reported to occur when local increasesin temperature are sufficient to initiate the oxidation of the carbonand propagate as more heat is released by the exothermic reaction. Heatconfinement in nanostructures can thus lead to drastic structuralreformation and, under oxidizing environments, induce ignition underconditions not expected for bulk materials. The heat pulse is created bylight absorption by the nanotubes from a proximal light flash.

Applications of optical heating or ignition of carbon nanotubes arelimited by several characteristics of carbon nanotubes that includesize, high aspect ratio, insolubility in water or other liquids, andlack of biocompatibility. Compositions are needed that provide radiationinduced heating or ignition in water or other liquids as well as air,have small size and low aspect ratio, and are soluble in water or otherliquids. Moreover, preferably such compositions are biocompatible toallow use in medical applications.

SUMMARY OF THE INVENTION

A method of localized heating includes the steps of disposing aplurality of fullerene comprising molecules in at least one targetregion and irradiating the fullerene comprising molecules withelectromagnetic radiation having a wavelength and intensity sufficientto convert the radiation to thermal energy at the fullerene comprisingmolecules, heating the target regions. The fullerene comprisingmolecules can be heated to a state of combustion. The fullerenecomprising molecules can be endohedral fullerenes, substitutedfullerenes, functionalized fullerenes or any mixture of thesefullerenes. The target region is within or in contact with a materialthat can be an organic gas, liquid or solid; an inorganic gas, liquid,or solid; a polymeric or polymer composite; water, an aqueous solutionor aqueous suspension; a metal or metal alloy, a glass or ceramic; or abiological or biologically derived material or mixture of thesematerials. The electromagnetic radiation can be at least one of gammarays, x-ray, extreme ultraviolet, ultraviolet, visible, infrared,microwave or radio-wave radiations.

The method can be used as a photoresist where the target region iswithin a resist coating, with the fullerene comprising moleculesdisposed within or contacting the coating where negative features orvoids can be formed in the resist coating by thermally induceddecomposition in the target regions of the coating when the heatingresults from irradiation of the target area. When irradiation results inthermally induced reactions or physical phase transformations in thetarget regions of the coating, an etchant can be used to remove thetarget region leaving negative features in a coating or channels withinthe coating. When the irradiation induces reactions, such as thermalcross-linking, an etchant can be used to remove all but the targetregions leaving positive features from the resist coating. Alternately,negative features can be created directly on a photoresist containingfullerene comprising molecules upon irradiation with no need for anadditional etching step. Alternately, a solution of fullerene comprisingmolecules can be used as a photoresist.

The method can be used for welding a plurality of polymer or polymercomposite pieces by irradiating the interface of the pieces using alaser beam with the fullerene comprising molecules disposed within orcontacting the interface so that the polymer at the interface melts andfuses into the weld upon cooling.

The method can be used for soldering where the heat generated uponirradiation of the fullerene comprising molecules within or contactingthe solder melts the solder at the target region. Soldering of surfacescan be carried out remotely in this manner.

The method can be employed for alternate and enhanced methods of writingto writable memory media such as CDs and DVDs. The fullerene comprisingmolecules can be at or in a layer of an organic dye or a metal alloy toamplify and accelerate the physical or chemical changes of the targetregions of the layer that changes optical properties of the layer in thetarget region to encode information. Such changes can be reversible orirreversible. The layer can be fullerene comprising molecules withoutthe dye or alloy such that decomposition of the fullerene comprisingmolecules in the target region of the layer results in irreversible orreversible changes in the optical properties of the layer in the targetregion.

The method can be employed in a device to act in a manner similar to aspark plug where the target region is an end of a tube filled with thefullerene comprising molecules and where the end of the tube is incommunication with a combustion chamber. When the combustion chambercontains a fuel-oxidizer mixture, irradiation of the end of the tube bya laser beam can result in ignition of the fullerene comprisingmolecules and the fuel oxidizer mixture in the chamber. The device canalso have a plunger in the tube to move uncombusted fullerene comprisingmolecules to a position at the end of the tube for a subsequent ignitionin the chamber.

The method can also be used where fullerene comprising molecules aredissolved or suspended in a fuel prior to introduction to a combustionchamber such that an irradiation in the chamber results in ignition ofthe fullerene comprising molecules and the fuel oxidizer mixture. Such afuel and ignition system would have little or no temperaturesensitivity.

The method can be used for detection and destruction of hazardousbioparticulates where fullerene comprising molecules, which contain aportion that is an aptamer or antibody or functionalized fluorescentantibody or dye/quantum dot doped silica particle, are contacted withthe bioparticulates. Where a plurality of fullerene comprising moleculesconjugate to a bioparticulate, low intensity irradiation promotesfluorescence of the conjugated bioparticulates to locate the targetregions and once located a sufficiently intense directed irradiation ofthe located targets can ignite the fullerene comprising molecule anddestroy the bioparticle.

The method can be used to target cancer cells within a patient. Thefullerene comprising molecules can be directed to the target region ofcancer cells and upon irradiation of the target region cause the cancercells to undergo apoptosis or necrosis, or to burst or to suffer otherconsequences of heating or ignition so that their growth is inhibited.One method of directing the fullerene comprising molecules to the cancercells is to have a targeting group as part of the fullerene comprisingmolecule where the targeting group associates the fullerene comprisingmolecule with the cancer cells. Radiation can be used to activate thefullerene comprising molecules thermally to destroy the target withoutpromoting damage to non-targeted regions of tissue.

The method can be used for initiation of an explosion. The fullerenecomprising molecules in direct or indirect contact with an explosivematerial can be combusted by irradiation to detonate explosivematerials.

The method can be employed as a micro or nano-thruster where the targetregion contains fullerene comprising molecules and optionally anotherpropellant, such that upon irradiation of the target region they combustto generate gases that provide a thrust.

The method can be used for solar heating application where the fullerenecomprising molecules decorate the surface of a metal. Solar irradiationof the decorated surface causes heat to be transferred to the metal andultimately to water or another medium on the opposite side of the metal.

A system for heating a target region includes at least one fullerenecomprising molecule disposed in the target region with an irradiationsource that can direct radiant energy to the target region as desired.The irradiation can be from any source, such as a laser, a lamp, orsunlight. The period of irradiation can be controlled by a switchactivated either manually or automatically controlled by a computer orother device, by opening and closing a shutter situated between a sourceof radiant energy and the target region, again activated either manuallyor automatically.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show the structure of exemplary functional fullerenes ofvarious embodiments of the invention, C₆₀(OH)_(n)(n˜1-48) andC₆₃(COOH)₆, respectively.

FIG. 2 shows an image of a bubble (resulting from localized heating) bylaser ignition of Polyhydroxyl fullerenes (PHF) that were placed on topof lung mesothelial carcinoma cells (A549).

FIGS. 3A, 3B, 3C, and 3D show images before, 1 second after, 10 secondsafter, and nearby cells 10 seconds after radiation induced ignition ofPHF coated folate conjugated silica nanoparticles in A549 cells,respectively.

FIGS. 4A, 4B, and 4C, are images where FIG. 4A is a photographic imageof a front side view of PHF coated paper with “UF” inscribed usingoptical ignition of PHF according to the invention; FIG. 4B is an imageshowing that the width of the inscribed line (50 μm) is close to thebeam spot size of the laser used; and FIG. 4C is an image showing theback side of PHF coated paper with “UF” inscribed, showing that thepaper was burned through to the back side by the optical ignitionphenomenon.

DETAILED DESCRIPTION OF THE INVENTION

A method of remotely activated localized heating comprises the steps ofdisposing a plurality of fullerene comprising molecules in a targetregion. The fullerene comprising molecules are irradiated withelectromagnetic radiation having a wavelength and intensity sufficientto heat, and in some embodiments heating is accompanied by combustion ofthe fullerene comprising molecules. The fullerene comprising moleculesabsorb radiant energy and convert the radiant energy into thermal energyto supply heat to the target region.

The present invention is based on the unexpected finding that fullerenecomprising molecules, upon irradiation using a suitable source, heat,ignite or combust without the need for a spark, flame or otherconventional initiator to produce significant local heating. Heating orignition can occur in a gaseous, liquid, or solid environment. In air,the ignition leads to rapid decomposition. A bright flash of visiblelight can be observed before combustion. The heating can be nearlyundetectable as a temperature increase in some environments. As isreadily understood by those skilled in the art, a photo-induced thermaleffect need not dissipate the thermal energy as a temperature increase,but can also be dissipated as a different thermodynamic parameter, suchas a pressure change. In some environments, the irradiation of thefullerene comprising molecules can generate heat that causes expansionof the fullerene which then dissipates a significant portion of theenergy as a pressure wave, a photoacoustic effect, rather than by asignificant temperature increase. The resulting heat induced change tothe target region can be due to a photoacoustic shockwave exclusively orin combination with a temperature increase, particularly in someembodiments of the invention where biological cells are disrupted.Stated otherwise, the thermal energy caused by photon absorptiongenerates vibrational or other induced intra- or extra-molecular motion,which generates heat and pressure changes that affect the target region.

Although the visible and near infrared (NIR) radiation has beendemonstrated to provide significant heating including ignition accordingto embodiments of the present invention, other wavelength ranges couldprovide significant heating or ignition. For example, IR radiationgenerally, as well as UV, microwave and radio-wave radiation can beuseful for producing significant heating or for inducing ignition.

Fullerenes are generally in the form of a spheroidal carbon comprisingstructure and are thus distinct from carbon nanotubes, which areessentially tubes with graphene surfaces. In contrast to the surface ofcarbon nanotubes, fullerenes have both five carbon and six carbon ringstructures. Carbon nanotubes and fullerenes are physically andchemically stable molecules. Unlike carbon nanotubes and fullerenes,some functionalized fullerenes are known to be biocompatible and canhave therapeutic properties.

The term “fullerenes” defines a general class of molecules that existsessentially in the shape of a three dimensional polyhedron containingfrom 20 to 1500 carbon atoms, and which comprises carbon atoms as thepredominant atomic moiety from which they are composed. The fullerenecomprising molecules include but are not limited to fullerenes such asC-28, C-32, C-44, C-50, C-58, C-60, C-70, C-84, C-94, C-250 and C-540.(According to this nomenclature, the fullerene which contains 60 carbonatoms is denoted C-60, the fullerene which contains 70 carbon atoms isdenoted C-70, etc.) Also included among the fullerene comprisingmolecules for purposes of the invention are the substituted fullerenes.These are molecular fullerenes which have had one or more of the atomswhich comprise the fullerene cage structure replaced by an atom otherthan carbon, yet essentially retain the geometry of a polyhedron uponbeing so substituted. Also included among the fullerene comprisingmolecules for the purpose of the invention are endohedral fullerenes, inwhich atoms of elements other than carbon (e.g., iron) reside inside thecage structure of fullerenes. The fullerene comprising molecules for thepurpose of the invention also include functionalized fullerenes, inwhich different functional groups are bonded to the fullerene cage viacovalent bonds, or ionic bonds, or Dewar bonds, or Kubas interactions,or mixtures of these bonds. Functionalized fullerenes refer tofullerenes (C_(x) where x is 20 to 1500) with side groups attached tothe cage. The side groups can be either inorganic, including but notexclusive to —OH, —Br, —H, —Ti, or organic, including but not exclusiveto —C(COOH)₂ or combinations of organic and/or inorganic. The number ofside groups attached per cage of fullerene can vary from 1 to a majorityof the number of carbons in the fullerene cage. Functionalizedfullerenes have different physical and chemical properties based on thetype and number of side groups. The fullerene comprising molecules havedimensions that can be in excess of a nanometer in diameter, and can beconsidered nanoparticles.

In one embodiment of the invention, functionalized fullerenes do nothave nitrogen in their structure, and have no measurable metalimpurities associated with them. Two exemplary, but non-limiting,functionalized fullerenes are described in some detail below. Both ofthese fullerenes are generally commercially available.

Polyhydroxyl fullerene derivatives (PHF), for example formulaC₆₀(OH)_(n) (n˜1-48) shown in FIG. 1(a) were first reported by Chiang,L. et. al. (J. Chem Soc, Chem. Commun. 1992, 1791). PHF, also referredto as fullerols or fullerenols, are useful for the formation of gels,starburst polymers, and composites and may be used as therapeutics. Thenumber of —OH groups is typically between 1 and 48. Polyhydroxyfullerene derivatives can be further derivatized to form otherfunctionalized fullerenes according to embodiments of the invention. Forexample, the OH can be converted into ethers or esters to yieldfunctionalized fullerenes with enhanced miscibility with aqueous ornon-aqueous environments.

Carboxy fullerenes, for example formula C₆₃(COOH)₆ shown in FIG. 1(b),are water soluble and are reported to have therapeutic properties byDugan et al. (Proc. Natl. Acad. Sci., 1997 Vol 94, 9434-9439). Againsuch carboxy fullerenes can be further derivatized, for example byesterification or amidation reactions, to form other functionalizedfullerenes for use in various embodiments of the invention.

Other exemplary functionalized fullerenes include N-ethyl-polyamino-C60,[6, 6] phenyl C60 butyric acid methyl ester (PCBM), fullerene hydrideand N-methyl fulleropyrrolidine. Certain polymer chains can also be usedas functional groups.

Highly localized heating provided by the method of the invention can beused for a wide variety of useful applications. For example, in oneembodiment of the invention fullerene comprising molecules can be usedfor photolithography. The water-soluble nature of some functionalizedfullerenes, such as PHF, can be used to coat a variety of substrates andcan be removed using water upon completion of an etching step of aphotolithography process. Alternately, functionalized fullerenes solublein a different solvent suitable for photolithography can also be used.Current nanolithography is usually carried out by e-beam lithography(commercial scale), focused ion-beam and dip-pen lithography. The lattertwo are not performed commercially since the processes are quite timeconsuming. E-beam lithography depends on the energy of electron beambreaking the polymer chains of the resist film.

Functionalized fullerenes, such as PHF, can be used as a component in acoating system on a resist according to an embodiment of the inventionwhere the process can operate at atmospheric pressure and becost-effective because radiation such as x-ray, UV, visible, NIR, andmicrowave over a range of wavelengths can be absorbed by the fullereneparticles. Functionalized fullerenes can be included in the coatingsystem above or below the resist or mixed with the resist as long as thelaser or other radiation source can be focused on them. The minimumwidth achieved by e-beam nanolithography is now about 20 nm. The etchingas a result of heat generated by localization in functionalizedfullerene molecules can be controlled by the spot size of theirradiation. In principle, the line width achieved through etchingaccording to the invention can be as small as 1.0 nm, which is thecross-section of a functionalized C-60 molecule. Fullerenes of lowercarbon number have smaller cross-sections. Ignition or heating of thefullerenes to a degree where the coating undergoes thermal degradationcan form negative features in the coating. Heating provided byfullerenes according to the invention which is short of ignition caninduce other changes in the coating system. For example, this phenomenoncan be applied in nanolithography for assisting in a chemical etching,for example a caustic etching of a polymer resist or a physical etching,for example a heat and/or vacuum promoted volatilization of a polymerresist, where the change can either act as a positive resist where onlythe irradiated features remain after etching or a negative resist whereonly the irradiated features are removed by etching. A coating offunctionalized fullerenes applied directly to a wafer or MEMS/NEMSsubstrate can also be used as a resist for nanolithography; for example,a solution of PHF in water with viscosity enhancers can be coated as aresist.

In one embodiment, the inventive coating can be used to create nano ormicrofluidic devices or to create nanoscale patterns by nanolithography.Functionalized fullerenes comprising coatings, such as PHF coatings, canbe applied in other processes involving pattern forming, etching orcutting.

Functionalized fullerenes according to an embodiment of the inventionsuch as PHF can also be used for polymer welding. The welding method caninclude functionalized fullerenes included in a polymer composite oradhering to an edge of a polymer. When two or more pieces withfunctional fullerenes situated within or at the interface of twocontacting surfaces are irradiated, local melting occurs at theinterface in the region about the functionalized fullerenes. For examplethe interface between two polymer pieces with functionalized fullerenescan be irradiated selectively by a laser at an intensity that causesheating without ignition of the functionalized fullerenes to melt thepolymer at the interface with the formation of the weld upon cooling.

In another embodiment of the invention the optical heating or ignitionproperties of functionalized fullerenes can be used for localizedsoldering on various substrates. One example of an application ofsoldering with functionalized fullerenes is micro-hole repairs invessels. Functionalized fullerenes can be included in a thin tape, orother patch structure, such that an alloy with a low melting point canbe applied to an area for repair. Laser irradiation of the tape caninduce localized melting of the tape such that the molten tape can sealmicro-holes. In this embodiment the functionalized fullerenes can bemixed with a soldering alloy and laser irradiation of the functionalizedfullerenes can generate heat for soldering. The method provides analternative to electrical heating for soldering. An advantage of using aradiation source to melt solder instead of electrical heating is evidentfor under-water soldering applications. Such soldering can be carriedout remotely using a laser such that no human presence at the point ofsoldering is required. Remote soldering can find applications in repairof spacecraft such as satellites, space stations and interplanetarytransport vehicles.

One technology that can be impacted by the inventive method is that ofwritable memory media such as compact discs (CDs) and digital videodiscs (DVDs). A writable CD or DVD, typically comprising an aluminumlayer with a coating of translucent organic dye, is written by creatingpatterns of opaque features with a laser light at 780 or 650 nm,respectively. A rewritable CD or DVD typically uses a metal alloyinstead of organic dye layer where a laser induced heating causes aphase change in metal alloy from crystalline to amorphous to create thelight and dark digital pattern. A Blu-ray disc also employs phase changealloys for writing purposes using a 405 nm wavelength laser. Alternativedisc technologies that can be used for writable memory media includefluorescent multilayer disc, 3D optical data storage, and polar highdefinition DVD. The common feature of all such technologies is the useof a laser for writing information by laser induced heating of a layerwithin the disc.

In one embodiment of the invention, a coating of functionalizedfullerenes such as PHF on an organic dye or alloy layer of these discmemory devices can improve both writing speed and efficiency. In anembodiment for writable discs, the intensity of the laser can be higherthan the threshold value for localized optical ignition of thefullerenes. In another embodiment for rewritable discs, the intensity ofthe laser can be attenuated to cause only localized heating offunctionalized fullerenes without optical ignition.

In another embodiment coating of functionalized fullerenes can beemployed as the sole layer for writing of digital information similar toprotein coated discs. For reference, the size of the protein,bacteriorhodopsin, used in a protein coated disc, is around 3 nmallowing data storage greater than 1 Terabyte/inch². The size offunctionalized fullerenes which can be decomposed during writing(“burning”) is typically smaller than bacteriorhodopsin protein (about 1nm versus about 3 nm), potentially allowing 9 times more information tobe stored. The digital information can be read from the disc withtechniques similar to those employed for protein-coated discs.

In an embodiment of the invention, the optical ignition property offunctionalized fullerenes can be utilized for a spark-plug-likeapplication. An example of a device is described as follows.Functionalized fullerenes such as polyhydroxy fullerenes (PHF) can bepacked in a small tube with one end having small orifice and a means todeliver fullerene comprising molecules to the orifice in contact with acombustion chamber. A laser source (e.g., LED laser) of any wavelengthis located nearby with the laser beam pointed towards the orifice. Tostart ignition the laser is turned on so that the laser beam illuminatesthe PHF particles present at the end of the tube. The laser irradiationcan be in the form of a high intensity short pulse. Optical ignition atthe end of the tube initiates combustion of the fuel-oxidizer mixture ina combustion chamber in a manner analogous to that of a spark plug in aninternal combustion engine cylinder. The other end of the tube cancontain a means, for example a plunger or a screw system, which deliversthe PHF particles towards the orifice. The length of the tube can beadjusted to vary the interval at which the tube must be replaced orrefilled with PHF. One of the major advantages of such a device overconventional spark plugs is operating temperature insensitivity.Conventional spark plugs are known to be less effective at lowtemperatures. The proposed device with functionalized fullerenes will befully operable at very low temperatures because the mechanism ofignition differs in a significant fashion from that of conventionalspark plugs (optical ignition vs. high voltage spark).

In one embodiment of the invention functionalized fullerenes can be usedas fuel additives to improve the combustion properties and efficienciesof fuels, increasing the energy density of liquid fuels without alteringtheir volatility. Such functionalized fullerene fuel additives canenhance combustion of the fuel at extremely cold temperatures. In such acase, the fuel with added functionalized fullerenes need only be used toinitiate and establish stable combustion, switching to fuel free offullerenes once combustion stabilizes in the warm engine. Anotherapplication for the fuels with added functional fullerenes is for usewith unmanned air vehicles (UAVs). Increasing the energy density of thefuel would give UAVs longer ranges or loiter times. Use offunctionalized fullerenes that are soluble in the fuel matrix wouldenable the energy density to be substantially increased with minimal orno change in fuel volatility or other properties.

Regarding medical applications, the present invention allows thedelivery of remotely controlled heat instantaneously to regions within ahuman or animal body where functionalized fullerenes can be placed. Thiscan permit precise methods for nanosurgery and nanotherapy. For example,cancerous tissues and cells can be selectively destroyed by use ofexternal electromagnetic fields and radiations that release intenseenergy from the functionalized fullerenes but otherwise are harmless tothe body. The functionalized fullerenes can be placed within the body bya variety of means, for example, when chemically attached tonanoparticle or other nanoscale object, and readily moved through thebody and can have specific groups to target and attach to cancer cells.

In one embodiment of the invention, functionalized fullerenes can beconjugated with targeting agents, for example fluorescent antibodies ordye/quantum dot doped silica particles functionalized with antibodies oraptamers, and exposed to hazardous bioparticulates such as bacteria,virus, and spores. For example, carboxy fullerenes along withfluorescent dye or quantum dots can be encapsulated in a silica matrix.The surface of the matrix can be conjugated with targeting agents suchas aptamers and antibodies. These multifunctional particles can then bedispersed in air or water for detection of hazardous bioparticulates,such as anthrax spores. The targeting agent can be used for the bindingof the multifunctional particles on the surfaces of the bioparticulates.Irradiation with a low intensity electromagnetic source at an excitationwavelength of a dye or quantum dot can permit detection of hazardousbioparticulates by localized, relatively intense emissions from exciteddyes or quantum dots that are part of multifunctional particlesaggregated on the hazardous bioparticulates. The intensity of theelectromagnetic source can be increased to heat, often causing aphotoacoustic wave or igniting the functionalized fullerenes andinactivate the bioparticles.

In one particular embodiment, hyperthermia, or photothermal ablation, isrealized using near-infrared radiation (NIR). Alternately, otherfrequencies can be employed, including radio frequencies in oneembodiment of the invention. PHF molecules can be internalized by cancercells through site targeted delivery. The internalized PHF can be thenirradiated with a NIR source, such as a NIR laser. Since NIR canpenetrate tissue, the technique can be non-invasive. Irradiation abovethreshold energy will lead to heating of PHF, increasing the temperatureor generating a photoacoustic wave inside cancer cells that issufficient to kill them. Currently, magnetic and gold nanoparticles arethe most promising candidates for hyperthermia. Both types ofnanoparticles are usually coated with a biocompatible layer andconjugated with targeting molecules. Applied magnetic/electric field andnear IR are used for initiating temperature rise in these nanoparticles.However, little attention has been given to the fate of thesenanoparticles. These nanoparticles can circulate in the body aftertreatment for a long period of time depending on the rate and mechanismof clearance. In contrast, PHF molecules according to the invention canbe decomposed by a radiation induced ignition used to generatehyperthermia, allowing them to be readily eliminated from the system.Any excess of PHF nanoparticles circulating in the body can be non-toxicsince PHF has been reported to display therapeutic properties such as anantioxidant, possibly reducing stress on the non-targeted cells andtissues.

Lasers have many applications in surgery including Laser-Assisted inSitu Keratomileusis (LASIK), laser-tissue welding (LTW), laser-tissuesoldering (LTS), laser resurfacing and use of laser scalpels for cuttingtissues or tumors (photodynamic therapy). One major side-effect oflasers is overheating, and in some cases thermal damage, of nearbytissues. Gold nanoshells have been employed for LTW and LTS to improvedeep tissue heating and reduce thermal damage to surrounding tissues. Inone embodiment of the invention, optical heating or optical ignitionproperties of functionalized fullerenes can be exploited for surgery inplace of gold nanoshells to reduce the intensity of laser needed forlocalized heating or cutting of tissue, thereby limiting or preventingdamage to surrounding tissues. Functionalized fullerenes can be useddirectly for these laser assisted embodiments or can be encapsulated ininorganic matrices, such as silica or titanium dioxide, or organicmatrices such as poly(lactic-co-glycolic acid (PLGA) or chitosan.

In another embodiment of the invention functionalized fullerenes can beused as an explosion initiator. PHF, for example, can be ignited usingradiation in excess of an intensity threshold. Radiation inducedignition is preferred for initiation of explosions as it is immune toelectrical effects and is chemically stable. Conventional explosivesrequire intensity on the order of GW/cm² for radiation inducedinitiation of an explosion. In comparison PHF can initiate theequivalent explosion with intensities on the order of kW/cm², thusdecreasing the size and energy requirement of the radiation source. Amajority of conventional explosives have nitrogen in their molecularstructure. Certain bonds of nitrogen (N—N, NO₂) are unstable, whichimparts instability to their structure. This instability is harnessedfor explosive action. PHF and other functionalized fullerenes accordingto an embodiment of the invention do not have nitrogen atoms in theirstructures and the ignition is hypothesized to be due to localization ofheat inside the molecule. Oxygen present in the PHF molecule may help indecomposition.

The explosion initiated from a fullerene comprising molecule can takeplace on a nanoscale or microscale fashion where a solid material isripped or otherwise fractured from a pressure wave when the thermalenergy is dissipated by a photoacoustic effect. These “nanoexplosions”can occur with the generation of a tortuous surface emanating from thefullerene comprising molecule.

In another embodiment of the invention, the optical heating or ignitionof functionalized fullerenes can be used to provide a thrust vector. Therate of thrust can be modulated according to the quantity offunctionalized fullerenes that is irradiated. In this manner the opticalheating or ignition property of functionalized fullerenes can be usedwith or without other propellant for micro-thruster and nano-thrustersin space for precise positioning and rotation of satellites or otherspace vehicles. The functionalized fullerenes can be used exclusively asigniter and propellant or used in combination with other propellantssuch as polyvinyl chloride, polyglycidyl azide or polyvinyl nitrate.

In another embodiment of the invention, because functionalizedfullerenes can absorb radiation across all wavelengths and release theabsorbed energy as heat, the radiation absorption property offunctionalized fullerenes can be utilized for solar heatingapplications. Functionalized fullerenes can be applied as a coating onmetal, for example copper, surfaces of solar heaters for increasing theefficiency.

EXAMPLES

It should be understood that the Examples described below are providedfor illustrative purposes only and do not in any way define the scope ofthe invention.

Example 1

Functionalized fullerenes, such as polyhydroxy fullerenes (PHF) andcarboxy fullerenes (CF) were found to ignite when exposed to radiationthrough a wide range of visible and NIR wavelengths above a thresholdintensity. Ignition led to instantaneous decomposition in air. Theignition process for PHF was observed with laser radiation at threedifferent wavelengths; 785 nm (Near Infrared), 540.5 nm (Green) and 488nm (Blue). The radiation induced ignition experiment with carboxyfullerenes and N-ethyl-polyamino-C60 was conducted with a 785 nm Laser.In both cases, the threshold intensity for observed ignition was lessthan 1 kW/cm².

Example 2

Experiments were conducted with A549 (Lung Mesothelial Carcinoma) cells.In a first step, varying quantities of PHF were placed on top of amultilayer of A549 cells cultured on magnesium fluoride crystals. Thecells were submerged in aqueous growth media RPMI-1640, supplementedwith 5% Fetal Bovine Serum and 1% Antibiotic, and exposed to a laseremitting at 785 nm wavelength. Sparking was observed at the focal pointfollowed by popping sounds, which was attributed to eitherphoto-acoustic effect or bursting of A549 cells. The observed damage tocells was dependent on the concentration of PHF. The damage wasrestricted to the top layer of cells at lower concentrations of PHF,whereas at higher concentrations of PHF, the ignition led to damage ofmultiple layers of cells as shown in FIG. 2, which shows a bubblecreated by laser ignition of PHF and clearly demonstrates the killing ofthe cancer cells.

Example 3

Another set of experiments was conducted with PHF coated on folateconjugated silica nanoparticles. The folate conjugation assists inuptake of nanoparticles by living cells, particularly cancer cells. ThePHF coated nanoparticles were incubated for 24 hours with A549 cells ingrowth media for internalization. The A549 cells in the media were thenexposed to radiation from a 785 nm laser for 1 second and 10 seconds asshown in the series of images presented in FIG. 3. After one second ofexposure, the irradiated A549 cells appear granulated suggesting thatthe cells are under stress and in the process of cell death. Thisindicates that heating, short of ignition, of functionalized fullerenescauses granulation of associated cells. Further irradiation with thelaser, for 10 seconds, resulted in radiation induced ignition andcreation of a bubble. However, nearby cells were not affected,suggesting that hyperthermia can be controlled by focusing of theradiation.

Example 4

Preliminary experiments were conducted with PHF coated paper. Thecoating was created by adding 50 microliters of PHF solution (1000 ppmin water) on paper which was subsequently dried. The coated paper wasthen exposed to laser radiation at 785 nm. The paper was manually movedto inscribe “UF” on paper. It is important to note that uponirradiation, the ignition of PHF and burning of paper was limited to thearea of the laser spot. However, the heat generated was sufficient toburn the paper which evidences a temperature of >240° C. The degree ofpenetration of the inscription can be controlled with the concentrationof PHF and intensity of irradiation. At higher concentrations of PHF orhigher intensity of radiation, the “UF” pattern was burnt through thepaper and could be observed on the backside of the paper as shown inFIG. 4(c).

Example 5

Fullerene comprising molecules were demonstrated to cause nanoexplosionsin a nanocomposite of poly(methyl methacrylate) (PMMA) and polyhydroxyfullerenes (PHF) by an apparent photoacoustic wave emanating from theirradiated PHF. The PMMA-PHF nanocomposite displayed a dark brown colorresulting from PHFs. Upon irradiating the PMMA-PHF nanocomposite with a785 nm laser at about 10² W/cm² a debris field formed after seconds ofexposure, indicative of an explosion due to photoacoustic pressure orshock-wave.

It is to be understood that while the invention has been described inconjunction with the preferred specific embodiments thereof, that theforegoing description as well as the examples which follow are intendedto illustrate and not limit the scope of the invention. Other aspects,advantages and modifications within the scope of the invention will beapparent to those skilled in the art to which the invention pertains.

We claim:
 1. A method of localized heating within an article, comprisingthe steps of: disposing a plurality of functionalized fullerenesselected from endohedral fullerenes, polyhydroxyl fullerenes, carboxyfullerenes, N-ethyl-polyamino-C60, [6,6] phenyl C60 butyric acid methylester (PCBM), fullerene hydride, N-methyl fulleropyrrolidine, or anycombination thereof disposed in or on at least one target region; andirradiating said functionalized fullerenes with electromagneticradiation to convert said radiation to thermal energy wherein saidthermal energy dissipates as a photoacoustic wave emanating from saidfunctionalized fullerene comprising molecule; and inducing a change insaid target region by said photoacoustic wave.
 2. The method of claim 1,wherein said target region is within a patient, said target regionincludes cancer cells, wherein said thermal energy at said target regioncauses said cancer cells to undergo apoptosis, necrosis, bursting orother transformation that inhibits growth of said cancer cells.
 3. Themethod of claim 1, wherein said functionalized fullerene is furtherfunctionalized with at least one targeting agent selected from aptamer,antibody, functionalized fluorescent antibody, and, optionally, furtherfunctionalized with dye/quantum dot doped particle.
 4. The method ofclaim 3, wherein said functionalized fullerene conjugates with abioparticle in said target region, wherein said irradiating comprises afirst irradiating with a low intensity of said electromagnetic radiationto promote fluorescence to locate said target regions and a secondirradiation of said target region with sufficient intensity toinactivate said bioparticle upon absorption of said thermal energy. 5.The method of claim 3, wherein said targeting agent associates saidfullerene comprising molecule with said cancer cells.
 6. The method ofclaim 1, wherein said target region is within a patient, wherein saidinducing a change in said target region is splitting or welding tissueis said target region.